Collaring timing control system for rock drills

ABSTRACT

An automatic control system for a guide shell mounted rock drill including a control circuit having pneumatically operated valves for providing pressure fluid to the drill hammer, rotation motor and feed motor and for controlling drill hole flushing medium. Sensors mounted on the drill guide shell provide for reversal of the feed motor and reduced drill power upon reaching the forward end of the guide shell, and shutdown of the drill upon reaching the rearward end of the guide shell. The control circuit includes a series of control valves for selection, at will, by the drill operator of a particular operating sequence or condition of the drill. A control valve is included for providing an operating sequence which includes operation of the drill at reduced power for a predetermined period of time for collaring a drill hole. The control system also includes pressure proportioning valves for automatically regulating the feed motor pressure to be proportional to the drill percussion motor supply pressure.

llnite States atent Hanson et al.

[72] Inventors: Laurence B. Hanson, Pine; Wallace W.

Arthur, Denver, both of Colo.

[73] Assignee: Gardner-Denver Company, Quincy, Ill.

[22] Filed: Sept. 11, 1970 [21] Appl. No.: 71,405

Related US. Application Data [62] Division of Ser. No. 808,925, Mar. 20,1969, Pat. No.

[52] US. Cl ..l73/ll2,91/28,9l/38, 173/159 [51] Int. Cl ..,..B25d 17/28,E21c 5/10 [58] FieldofSearch ..91/38, 28, 29; 1731/1, 112, 173/115,l52,159,134

[56] References Cited UNITED STATES PATENTS 3,319,725 5/1967 Edwards..l73/l59 X 2,405,172 8/1946 Yanchenko ..91/38 X Primary Examiner-EmestR. Purser Attorney-Michael E. Martin [5 7] ABSTRACT An automatic controlsystem for a guide shell mounted rock drill including a control circuithaving pneumatically operated valves for providing pressure fluid to thedrill hammer, rotation motor and feed motor and for controlling drillhole flushing medium. Sensors mounted on the drill guide shell providefor reversal of the feed motor and reduced drill power upon reaching theforward end of the guide shell, and shutdown of the drill upon reachingthe rearward end of the guide shell. The control circuit includes aseries of control valves for selection, at will, by the drill operatorof a particular operating sequence or condition of the drill. A controlvalve is included for providing an operating sequence which includesoperation of the drill at reduced power for a predetermined period oftime for collaring a drill hole. The control system also includespressure proportioning valves for automatically regulating the feedmotor pressure to be proportional to the drill percussion motor supplypressure.

52 START I STOP I b a b In 72 L J /55 34 5 Claims, 5 Drawing Figures lll F i q I i I1 I F illil i i I I I r102 J l i, I i/37 H5] L38 1 /80 l ii H E. \L, k i j 1 4 a I I 1 H92 H36 l I421] /40 I f l l DRILL I 1IREVERSE1 b a 6817 68 I I 62 L 2L 1 M E E w c L 1.

90 92 g L '5? J COLLAR TIME l 3 Sheets-Shed 1 Patented May 30, 1972 NJmi k h 1 2 3* A X1 N r I I I r %N\ v v aw finnnunnnnn IL}? ifilfiil 1 WmQVM.

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3 Sheets-Sheet 2 Patented Ma 30, 1972 Patented May 30, 1972 3,666,025

3 Sheetgs-Sheet 5 COLLARING G CONTROL SYSTEM FOR ROCK lDRlLLS This adivision of application Ser. No. 808,925 filed Mar. 20, 1969 and now US.Pat. No. 3,561,542.

BACKGROUND OF THE INVENTION In underground mining and tunnelconstruction it is common practice to drill blast holes with multiplerock drill units commonly known in the art as jumbos. Jumbos usuallycomprise a plurality of pressure fluid operated percussion rock drillsslidably mounted on elongated supports known as guide shells which inturn are mounted on positionable booms. Operation of the rock drills isnormally controlled from a remote operator station or control panelmounted on a vehicle or undercarriage carrying the boom and drillassemblies.

Heretofore control of plural drills has been largely a manual operationcarried out by manipulation of a number of control valves located on theoperator control panel to feed and retract the drills along theirrespective guide shells and to regulate feed pressure and drill motorimpact and rotation. As the number of drills mounted on a jumbo isincreased, it becomes difficult for an operator to monitor and controlall drills simultaneously and accordingly drilling rates decrease andefficiency is impaired. It therefore becomes desirable to provide anautomatic control system for each drill so that a greater number ofdrills can be monitored by one operator.

An example of an automatic control system for a guide shell mounted rockdrill is disclosed in US. Pat. No. 3,381,761 to CA. I-Iansson. Inaddition to the automatic functions performed by the l-Iansson system itis desirable to provide for operating the drill at reduced percussionmotor impact power, feed rate, and drill steel rotation rate at thebeginning of the drilling cycle to collar or spot the hole.

Another problem associated with the operation of a guide shell mounteddrill is the regulation of the feed force to prevent overfeeding orunderfeeding the drill during penetration of the rock face. In largemines and tunneling operations the pressure fluid supply systems fromwhich jumbo units operate are often subject to supply pressurefluctuations which in turn make necessary the adjustment of the supplypressure to the feed motor to keep the feed rate of the drill at aproportional rate relative to the drill percussion motor power whichwill prevent overfeeding or underfeeding of the drill.

SUMMARY OF THE INVENTION The present invention provides for a rockdrilling apparatus having a control system which is operable to controlautomatically a predetermined operating cycle of the drill. The controlsystem of the present invention provides for an operating cycle whichcommences with operation of the drill percussion motor, feed motor, anddrill steel rotation motor at reduced power for a predetermined periodof time to collar or spot a hole. After the collaring operation iscompleted, the drill is automatically fed to the desired hole depth,then retracted along the support while operating at reduced power, andfinally shut off upon being fully retracted along the support.

The present invention also provides for control valve means which may beactuated to provide for continuous operation at reduced power to thedrill. The present invention also provides for control means operable toprovide full power to the drill percussion motor at any phase of thedrill operating cycle, reversing of the drill feed motor at any point inthe forward feed phase of the operating cycle, and stopping allfunctions at any phase in the drill operating cycle.

An important aspect of the present invention is the provision of valvemeans for automatically maintaining a regulated pressure to a drill feedmotor which is proportional to the drill percussion motor supplypressure to prevent underfeeding or overfeeding the drill due tovariations in pressure of the working fluid supply system.

Another aspect of the present invention is the provision of automatictime delay means operable to delay the retraction of the drill uponcompletion of the drill hole until sufficient hole cleansing medium hasbeen provided to flush the drill hole completely free of drill cuttingswhich could interfere with removal of the drill steel and bit, and sothat a clean hole is provided for ease in placing blasting chargestherein.

The apparatus of the present invention further provides for an improvedmethod of drilling blast holes wherein a complete cycle comprisingcollaring, drilling, cleaning the hole, and withdrawal of the drillsteel is accomplished automatically with predetermined time intervalsfor the collaring and hole cleaning phases.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 and FIG. 2 comprise a schematicview of the automatic control system and are intended to be readtogether.

FIG. 3 is a perspective view of an enclosure for the pilot operatedsupply valves.

FIG. 4 is a sectional view of an embodiment of a proportional pressureregulator valve for controlling pressure to a rock drill feed motor.

FIG. 5 is a sectional view of an alternate embodiment of a proportionalpressure regulator valve.

DESCRIPTION OF THE PREFERRED EMBODIMENT The schematic representation ofthe automatic control system shown in FIGS. 1 and 2 is for the purposeof ease in understanding the circuitry of the system. Generally,diagrams of valve and flow control elements are in accordance withaccepted standards for graphic symbols for fluid power diagramming.Exceptions have been made for nonstandard components and where standardsymbols are not particularly descriptive.

Referring to FIG. 1 an elongated drill support 10 is shown havingslidably mounted thereon a pressure fluid operated rock drill 12. Therock drill 12 includes a fluid operated rotation motor 14 operable torotate a hollow drill steel 16. The rock drill 12 is of a well knowntype which operates to deliver percussion blows to the drill steel 16 bymeans of a fluid actuated percussion motor 17 housed within the drill.The drill 12 is operable to use compressed air as the working fluidalthough the present control system with obvious modifications could beused with hydraulic working fluid. The drill support 10 also includes afluid operated feed motor 18 which is operable to feed the drill l2reversibly along the support 10 by one of several well known mechanisms,not shown.

A portion of the automatic control system of the instant invention isdiagrammatically shown as being contained in an enclosure 20 which couldtake many forms. One practical embodiment of such an enclosure isdescribed later herein in some detail.

The enclosure 20 has a main pressure air supply conduit 22 (see FIG. 2)leading from a source, not shown, into a first supply valve 26 having aposition a and a position b. All two position valves will be designatedas having a position a and position b. As an example to define thesymbols, the valve 26 has a spring actuator 26a to maintain the positiona and a pilot actuator 26b to maintain the position b when energizedwith pressure fluid. When pressure fluid is exhausted from the pilotactuator to deenergize the valve the spring actuator returns the valveto the position a. Quite conceivably, the pilot actuated valves of FIG.1 could have pilot actuators using a hydraulic or electric signal if thecontrol circuit were so designed to operate with these mediums. Numeral28 designates the flow restrictor and conduit which comprises aninternal pilot supply for pilot actuator 26b. A conduit 30 leads fromsupply valve 26 through an adjustable flow control valve 32 to the drillrotation motor 14. The main supply air conduit 22 has a branch 34 whichsupplies a second supply valve 36 comprising means to supply the drill12 with fluid at substantially supply pressure. The valve 36 is alsopilot air actuated and has an internal pilot conduit. The branch 34 isalso in communication via conduit 38 with a third pilot actuated supplyvalve 40 having an internal pilot conduit. The valve 40 comprises meansfor operating the drill and feed motor in the reverse condition. Alsomounted in the enclosure 20 is a twoposition pilot actuated valve 42 forcontrolling the supply of drill hole flushing water to the drill viaconduits 44 and 46. Drill hole flushing water is supplied internallythrough the drill 12 to the hollow drill steel 16 in a manner wellknown.

The enclosure 20 further includes valves 48 and 50 which compriseproportional pressure regulator means for regulating pressure fluid tothe feed motor. Valves 48 and 50 are shown schematically in FIG. 1 andstructurally in FIGS. 4 and S. A forward feed supply valve 52 which ispilot actuated to be in positions a or b is also included in theenclosure 20.

FIG. 1 also illustrates schematically a front position sensing elementcomprising a two-position mechanically actuated valve 54 having anactuator 54b engageable by the projection 56 on the drill 12. A rearposition sensing valve 58 similarly has an actuator 58b engageable bythe projection 60. The sensing valves 54 and 58 may be positioned asdesired along the length of the drill support and mounted thereon foractuation by the drill projections 56 and 60 to limit the forward andrearward movement of said drill by the automatic control system asexplained below.

Referring to FIG. 2, the remainder of the automatic control system isschematically illustrated as comprising a plurality of control valvesand associated circuitry housed within an enclosure 62 which wouldpreferably be mounted at the drill operator control station of the rockdrilling unit, not shown. The enclosure 62 has a branch conduit 64leading thereto which is in communication with the main air supply line22 and leads to the several control valves to be described. The operatorcontrol enclosure 62 houses a two-position valve 68 labeled COLLAR whichreceives supply air at line pressure from conduit 70 connected to branchsupply conduit 64. A typical manual operator or push button is depictedby the symbol 68b. The valve 68 may be actuated manually to the positionb or by a supply of pilot pressure fluid. Release of operator force orpilot pressure will result in the return to the position a. The controlenclosure 62 similarly includes two-position manual and pilot actuatedvalves 72, 74, and 76 labeled START DRILL and REVERSE, respectively. Thevalves 72, 74 and 76 are respectively connected to the branch supplyconduit 64 by conduits 78, 80 and 82. A manual and pilot actuated valve84 labeled STOP is also within the enclosure 62 for actuation by theoperator. The enclosure 62 further includes a pilot actuated exhaustvalve 86 and a similar exhaust valve 88.

An important aspect of the present invention includes a variable timingmeans which is provided for by the reservoir 90 and the adjustabletiming valve 92 labeled COLLAR TIME. The reservoir 90 is incommunication with the start valve 72 via the conduit 94, and with thepilot actuator of the drill control valve 74 by way of the conduit 96.The reservoir 90 also includes an orificed exhaust line 98. The conduit164, in communication with conduit 94, includes a typical check valve165. Flow is one way only as indicated by the arrow in conduit 164.

The circuitry can be easily traced and the control system can be bestunderstood by an explanation of the improved operating cycles which thedrill can be controlled to perform. From the accompanying drawings itwill be evident how the circuitry is interconnected to the variouscomponents. Referring to FIGS. 1 and 2 a normal drilling cycle beginswith the drill l2 retracted over the rear position sensing valve 58 sothat the valve is actuated to be in the position b. All valves labeledfor positions a and b will be in a position a except as noted. Watercontrol valve 42 is assisted to the position a by water pressure in line44' due to internal construction of the valve.

With pressure air supplied to conduit 22 and its branch conduit 64, airwill flow through conduit 100 to the rear sensing valve 58 and throughconduit 102 to the pilot actuator of exhaust valve 88 to hold the samein position b. Conduit 104 leading from conduit 100 to the frontposition sensor 54 will be bleeding through orificed conduit 106 tocontinually air wash the actuator 54b to prevent debris from collectingthereon. Air washing of the rear sensing valve actuator 58b occurssimilarly through orificed conduit 108. To commence a complete drilloperating cycle the operator will momentarily manually actuate the STARTvalve 72 shifting the same to position b which permits pilot air to flowfrom conduit 78 through conduit 110 to shift the first or collaringsupply valve 26 to position b (FIG. 1). Valve 26 then supplies airthrough its internal pilot 28 to maintain position b and pressure airflows through conduit 30 to operate the drill rotation motor at reducedspeed as controlled by the adjustable valve 32. Pressure air will alsoflow through conduit 111 through an adjustable flow control valve 112 toconduit 114 and to the drill 12 for operation of the percussion motor 17at reduced power. Valve 26 also supplies pilot air through conduit 116to hold the drill hole flushing water valve 42 open in position b toprovide water to the drill hole, and through conduit 118 to hold theforward feed valve 52 in position a. Supply air from conduit 118 alsoflows through the proportional pressure regulator 48 and conduit 119 tosupply fluid at proportionately reduced pressure through the forwardfeed valve 52 and conduit 120 to the feed motor 18. Referring to FIG. 1it appears that air can flow through conduit 111 and conduit 113 tooperate the internal pilot of the second or drilling supply valve 36 toshift same to position b and provide full power to the drill. However,the pilot actuator of valve 36 is set to operate at line pressure onlyand therefore will not actuate at the reduced pressure set by theadjustable valve 112. The drill 12 thus commences to operate at reducedforward force feeding for collaring the hole. Such operation isparticularly desired to prevent deflection of the drill steel when thesteel and bit are inclined to the surface of the rock face. As theprojection 60 moves off the actuator 58b of the rear sensing valve 58,said valve returns to position a and exhaust valve 88 returns toposition a.

As previously mentioned the operator need only actuate the START valve72 momentarily whereupon release of the manual actuator the start valvereturns to position a The collating supply valve 26, having shifted toposition b, now also supplies air at line pressure from its internalpilot conduit 28, through conduit 110, valve 72 and conduit 94 to thereservoir 90 at a rate controlled primarily by the timing valve 92. Thesetting of valve 92 will regulate the amount of time required forpressure to increase in the reservoir sufficiently to cause the drillcontrol valve 74 to shift to position b. The reservoir 90 may take manyforms including being embodied in conduit 96 depending on the volumethereof. When the control valve 74 has shifted to position b air at linesupply pressure will flow through conduit 80 and conduit 124 to actuatethe drilling supply valve 36 to position b to supply air atsubstantially line supply pressure to the drill percussion motor 17through conduits 113 and 114. Air at line supply pressure will also flowthrough conduit 111 and bypass conduit 126 to conduit 30 to operate thedrill rotation motor 14 at full power. Conduit 113 will also supply airthrough conduit 128 and the proportional pressure regulator 50 which inturn will provide a regulated supply of pressure air through conduit129, the forward feed valve 52, and conduit 120 to the feed motor 18.The feed motor will be exhausting through conduits 130 and 132 and thethird or reverse supply valve 40 which is in position a.

The drill 12 will proceed to operate at full power and will feed forwardalong the support 10 until the projection 56 strikes actuator 54bcausing the front position sensing valve 54 to shift to position b whichin turn will provide pressure air to flow through conduit 134. Conduit134 is in communication with an adjustable flow control valve 135 and areservoir 137 located in the control enclosure 62. A conduit 139 leadsfrom the reservoir 137 to the pilot actuator of the REVERSE controlvalve 76. The flow control valve 135 and the reservoir 137 comprise avariable time delay means to delay the shifting of the control valve 76to position b for reasons to be explained below. The REVERSE controlvalve 76, when shifted to position b by pilot pressure fluid fromconduits 134 and 139, will cause pressure air to flow through conduits82 and 136 to the pilot actuator of reverse supply valve 40 shiftingsame to position b. The REVERSE control valve 76 will also cause a pressure signal in conduit 138 to shift the exhaust valve 86 to position bexhausting air from the pilot actuator of the DRILL control valve 74 byway of conduits 140 and 142 causing valve 74 to shift to position awhich will cause a shift of the drilling supply valve 36 to position ainterrupting the full power supply to the drill percussion motor,rotation motor and proportional regulator 50. Collar supply valve 26will also actuate to position a having exhausted its pilot actuatorthrough conduit 1 10, START valve 72 in position a, conduit 165, 160,and 142 to the exhaust valve 86. The reverse supply valve 40 will alsonow supply pressure air through conduit 132 to conduit 144 shifting theforward feed supply valve 52 to position b exhausting conduit 120.Pressure air will also now flow through conduit 130 at full supplypressure to the feed motor 18 running the same in reverse to retract thedrill along the support. Pressure air is further now being supplied toconduit 146 and 148 simultaneously shifting the flushing water valve 42to position a shutting off the flow of water and changing the flushingmedium to air for drying the hole as the drill steel is withdrawn. Holecleaning air is not required to be controlled by valve 42 with thesystem of the present invention. The drill 12 is now also being suppliedwith a reduced supply of air through conduit 132 to adjustable valves 32and 112 to operate the rotation motor 14 and drill percussion motor 17at reduced power to facilitate withdrawal of the drill steel from thehole. After the drill projection 56 moves off the front position sensingactuator 54b the valve 54 returns to position a causing the pilotactuator of the REVERSE control valve 76 to exhaust through conduit 134and a shift of said valve to position a. The reverse supply valve 40remains in position b due to its own internal pilot supply.

The drill 12 continues to retract along the support until the projection60 strikes the rear position sensing actuator 58b causing the valve 58to shift to position b which in turn will send a pressure signal throughconduit 102 to the pilot actuator of the exhaust valve 88 shifting thesame to position b. The reverse supply valve 40 will now shift toposition a having exhausted its pilot actuator through conduits 136,138, and 150 and the exhaust valve 88. All supply air to the drill andfeed motor is now interrupted and the drill is shut down. The exhaustvalve 86 will also return to position a having exhausted its pilotactuator through conduits 138. The drill will thus have operated througha completely automatic cycle of operation with regulated pressure on thefeed motor 18 automatically compensating for variations in supply linepressure during the collaring and drilling phase of the cycle.

Various other operational modes are selectable, at will, by the operatorwith the control system of the present invention For example, if it isdesired to prolong operation of the drill at collaring power, that isprior to the drill engaging the front position sensing valve 54, manualactuation of the COLLAR control valve 68 to move to position b willoperate the pilot actuator of the START valve 72 by supplying pressureair through conduits 70, 152, and 154 to move the START valve toposition b. The collaring supply valve 26 will then be actuated aspreviously described and the drill will operate at collaring power. Uponactuation of the exhaust valve 86 to position b, caused by the drillactuating the front position sensing valve 54, the collar control valvepilot actuator would be exhausted through conduits 156, 160, 142 and thevalve 86 and the START valve 72 would return to position a afterbleeding its pilot actuator through conduit 154 and orifice 158. Duringany operating mode of the control system, full power to the drillpercussion motor and rotation motor may be applied by manual actuationof the drill control valve 74 to position b which will supply linepressure air to the pilot actuator of the drill supply valve 36 aspreviously described.

If the drill is in the reverse feed mode, however, the DRILL controlvalve 74 must be manually held in position b to operate the percussionmotor and rotation motor at full power, otherwise the drill supply valvepilot actuator would exhaust through the DRILL control valve, inposition a, and conduits and 142 and the exhaust valve 86 which, duringreverse feed of the drill, is in position b.

The control system may also be operated to commence the reverse feedmode at any point in the forward collaring or drilling mode by manualactuation of the REVERSE control valve 76 to position b. Such actuationwould cause a pressure signal to be sent to the reverse supply valve 40and via conduit 138 to exhaust valve 86 shifting both valves to positionb and resulting in operation previously described. With the controlsystem of the present invention only one control valve is required forreversing the feed motor which thereby eliminates the need for aso-called five-port four-way valve as found in certain prior artsystems.

Also, at any operating condition of the control system all pressure airto the drill and feed motor may be interrupted by manual actuation ofthe STOP control valve 84 to position b which will cause the COLLARcontrol valve 68 to exhaust its pilot actuator through conduits 156,160, and 162. The START valve 72 will exhaust through conduits 164, and162 and the DRILL control valve 74 will exhaust its pilot ac tuatorthrough conduits 140 and 162. The valves 68, 72, and 74 will thus returnto position a. The collar supply valve 26 and drill supply valve 36will, with their respective control -valves 72 and 74 in position a,exhaust their pilot actuators through STOP valve 84 and return toposition a. Reverse supply valve 40 will also exhaust its pilot actuatorthrough conduits 136, 138, 166 and 162, and through the STOP valve toreturn to position a. Therefore, regardless of the operating mode,actuation of the STOP valve to position b will result in theinterruption of the flow of pressure fluid to the drill, rotation motor,and feed motor. As shown in FIG. 2 the STOP valve may be operated from aremote pilot pressure air supply through conduit 170 as may the STARTvalve 72 by way of a pilot supply through conduit 172.

As previously mentioned, the adjustable valve 135 and reservoir 137operate as a variable time delay means to delay to pressure signalnecessary to shift the REVERSE control valve 76 to position b when thedrill projection 56 has actuated the position sensing valve 54 toposition b. This delay in operation of the REVERSE control valve and,consequently, the reverse supply valve 40 permits thorough flushing ofthe drill hole to assure the removal of all drill cuttings while thedrill steel is still at the bottom of the hole. As pressure fluid flowsthrough conduit 134 into the reservoir 137 the pressure would eventuallyincrease to a predetermined value required to operate the pilot actuatorof the REVERSE control valve 76 to shift said valve to position b andthe drill would be operated to retract along the support as hereinbeforedescribed. A conduit is connected to conduits 134 and 138 so that pilotpressure fluid is supplied to the actuator of exhaust valve 86 to effectthe closure of the drilling supply valve 36 without delay when the frontsensing valve 54 is actuated to position b. A check valve 182 preventspressure fluid from flowing into conduit 136.

A preferred construction of the enclosures 20 and 62 is illustrated inFIG. 3. The enclosure 20 is shown as consisting of a series of flatplate elements 184, 186, 188, and 192 assembled and fastened together byfasteners 194. All of the hereinbefore described conduits within theenclosure 20, as shown on the schematic of FIG. 1, would be drilled ormachined into the matching surfaces of the plates. All valve elementswould also be housed within the enclosure formed by the assemblage ofplates. This construction provides for a compact arrangement of valvesand conduits and also eliminates a large number of tube and pipefittings. The operator adjustment handles for valves 32 and 112 areshown protruding from plate 188 and the connections of pilot actuatorconduits 110, 124, and 136 are shown. The remaining eight connectionsrequired as shown by the schematic of FIG. 1 would be made on the bottomof plate 184, not shown.

The section view of FIG. 4 illustrates an embodiment of the proportionalpressure regulator valve 50 previously described and illustratedschematically in FIG. 1. The valve 48 of FIG. 1 is of similarconstruction. Referring to FIG 4, the valve 50 comprises a movableclosure member 200 having a stem portion 202 and a resilient seatingmember having an area forming a pressure surface 204. The closure member200 is interposed between conduits 128 and 129 formed by plates 184,186, and 188. The upper end of stem 202 projects through the end wall ofa spacer 206 pressed into the bore 208 in plate 188 and is threadedlysecured to a hollow piston 210. The piston 210, forming a part of member200, extends into the bore 212 of a cap 214 which is secured to plate188 by fasteners 216. An adjusting screw 218 is operative to vary thecompression of a coil spring 220 which is operable to bias the closuremember 200 in the closed position. The space 222 within the spacer 206is vented to atmosphere through passage 224. A passage 226 in the stemof closure member 200 communicates pressure fluid from conduit 128 tothe interior space 228 of the hollow piston 210 and to the bore 212 ofthe cap 214. The piston 210 is slidably housed in the bore 212 in closefitting relationship thereto and leakage of pressure fluid into space222 is desirably kept to a minimum. The piston 210 includes an area 230and an annular area 232 forming a second pressure surface operable tooppose the pressure acting on the surface 204 bounded by the seat 234.An annular area 236 formed on the closure member 200 comprises a thirdpressure surface and is operable to bias the closure member to theclosed position under the action of pressure fluid at the reducedpressure in conduit 129 acting thereon.

As previously mentioned it is desirable to maintain the feed motorpressure at a proportional value to the supply pressure to the drillpercussion motor to prevent underfeeding or overfeeding the drill whenfluctuations in supply pressure occur. In prior art drills it is often aproblem which requires the constant attention of the drill operator toadjust a manual valve to maintain the proper proportion. However, withthe use of the proportional pressure regulator 50 in the feed controlsystem of FIGS. 1 and 2 feed motor pressure is automatically maintainedat the desired proportional value. The valve 50 or its equivalent may,of course, be used with other rock drill control systems.

A single proportional pressure regulator valve of the type disclosedcould be used in the control system shown in FIG. 1. However, a systemof the type disclosed, having provisions for operating the drill atreduced pressure for collaring the hole, desirably has a separatepressure regulator due to the fact that the proportionality orpercentage value of feed motor pressure to supply pressure for collaringa hole is usually less than the value desired for operation at fulldrilling power. The provision of two regulator valves is thereforedesirable in a completely automatic system to eliminate the need foradjustment ofa single valve after the collaring phase of operation.

In operation of the valve 50, pressure fluid at supply pressureintroduced into conduit 128 would act on surface 204 to open the valveclosure member 200 permitting flow past the valve seat 234 to bethrottled to a reduced pressure into conduit 129. Pressure fluid atsupply pressure would also flow through passage 226 into space 228 andbetween the adjusting screw 218 and the inner wall of piston 210 intothe bore 212 to act on the annular area 232. Fluid at supply pressureacting on areas 230 and 232 and fluid at the reduced pressure in conduit129 acting on area 236 will operate to close the closure member 200. Byan algebraic summation of pressure forces acting on the valve closuremember 200 it may be seen that the areas 230, 232, and 236 may beproportioned such that the closure member will move to throttle flowacross the orifice formed by the closure member and the seat 234 until abalanced position is reached. Accordingly, the pressure in conduit 129may be regulated to a fixed percentage of the supply pressure in conduit128 regardless of what value the supply pressure may be. For example, ifthe sum of areas 230 and 232 is 70 percent of area 204 and the area 236is 90 percent of area 204 by setting the pressure forces on area 204equal to the pressure forces acting on the reduced areas 230, 232, and236 it may be realized that pressure will be regulated to be 33 percentof supply pressure. The areas 230, 232 and 236, of course, may bealtered in proportion to alter the reduced pressure. The spring 220 isused to provide a light biasing force to overcome friction of the closefitted piston 210 to close the valve. The biasing force of the spring228 may be increased by the adjusting screw to reduce the value of thereduced pressure, however, increasing the biasing force of the spring220 will also change the proportionality from a fixed percentage to avariable percentage. However, within the range of supply pressuresnormally encountered the variation in the reduced pressure will notadversely affect drill performance.

An alternate embodiment of proportional pressure regulator valve isillustrated in FIG. 5. The proportional pressure regulator valve 240includes a closure member 242 having a resilient seating member formingpressure surface 244 and a stem portion 246 threadedly attached to apiston 248 slidably housed in the bore 250 of cap 252. A passage 254leads from the bore 250 past an adjustable needle valve 256 to a passage258 opening to the exterior of cap 252. The piston 248 includes an area260 forming a second pressure surface, and an oriflced passage 262opening into the bore 250 from the conduit 128. The principle ofoperation of the valve 240 is similar to the valve 50, that is, a forcecaused by pressure fluid acting on area 244 of the closure member isopposed by pressure fluid acting on the piston area 260 and pressurefluid in conduit 129 acting on the annular area 264 forming a thirdpressure surface on the closure member 242. In operation, if the needlevalve 256 is closed the pressure in the bore 250 will be equal to supplypressure, and the reduced pressure in conduit 129 will be a fixedpercentage of the supply pressure in conduit 128 as determined by theproportioning of areas 260 and 264. If the needle valve 256 is open tobleed pressure fluid from the bore 250 the pressure therein will bereduced and the proportionality of the reduced pressure in conduit 129to the supply pressure in conduit 128 will be changed and will no longerbe a fixed percentage, but as with the proportional regulator valve 50in the range of pressures normally encountered the proper feed pressurecan still be obtained. Moreover, some adjustment of the proportionalitymust be provided for so that the drill operator can change the feedpressure for a given supply pressure to compensate for variations in thedrillability of different rock formations.

However, it should be noted that the biasing means of the respectiveregulator valves 50 and 240, that is, the spring 220 and the adjustmentscrew 218, and the pressure chamber and needle valves 256 operate in asomewhat different manner. The maximum value of reduced pressure thatcan be obtained with the valve 50 occurs when no biasing force isapplied by the spring 220, and an increase in the bias force acting toclose the member 200 will reduce the value of the regulated pressurewhich the valve 50 will operate to produce in conduit 129. In the valve240 the minimum value of reduced pressure is obtained when the needlevalve 256 is closed and the pressure acting on the surface 260 is equalto the supply pressure in conduit 128. By opening the needle valve toreduce the pressure in the chamber formed by the bore 250 the valveclosure member 242 will operate to balance at a higher value of reducedpressure in conduit 129.

What is claimed is:

1. Improved rock drilling apparatus comprising:

an elongated support;

a fluid operated rock drill movably mounted on said support and having apercussion motor operable to actuate a drill steel;

a fluid operated feed motor mounted on said support operable to feedsaid drill reversibly therealong;

a source of pressure fluid;

a conduit in communication with said source and said percussion motor;

flow control means interposed in said conduit operable to reduce thequantity of pressure fluid flowing to said percussion motor;

a first supply valve in said conduit actuatable to supply pressure fluidto said percussion motor for collan'ng a drill hole;

a second supply valve in communication with said source and saidpercussion motor operable to supply pressure fluid to said percussionmotor at substantially supply pressure; and,

control means operable to actuate said first supply valve to supply areduced quantity of pressure fluid to said percussion motor, saidcontrol means including timing means responsive to the actuation of saidfirst supply valve for operating said second supply valve after apredetermined time period commencing with the actuation of said firstsupply valve.

2. The invention set forth in claim 1 wherein;

said timing means is operable to vary said predetermined time period.

3. Improved rock drilling apparatus comprising:

an elongated support;

a fluid operated rock drill movably mounted on said support and having apercussion motor operable to actuate a drill steel;

a fluid operated feed motor mounted on said support operable to feedsaid drill reversibly therealong;

a source of pressure fluid;

a conduit in communication with said source and said percussion motor;

flow control means interposed in said conduit operable to reduce thequantity of pressure fluid flowing to said percussion motor;

a first supply valve in said conduit including a pilot actuator operablewhen supplied with pressure fluid to actuate said supply valve to supplypressure fluid to said percussion motor for collaring a drill hole;

a second supply valve having a pilot actuator and being in communicationwith said source and said percussion motor for supplying pressure fluidto said percussion motor at substantially supply pressure; and,

control means including timing means and a fluid circuit incommunication with said source and said first and second supply valvesfor supplying pilot actuator fluid thereto, a control valve in saidfluid circuit operable to be actuated to start said percussion motor bysupplying pressure fluid to actuate said first supply valve, and saidtiming means is operable to provide pressure fluid to actuate saidsecond supply valve after a predetermined time period commencing withthe actuation of said first supply valve.

4. The invention set forth in claim 3 wherein:

said drilling control circuit includes a control valve operable toprovide pilot actuator fluid to said second supply valve to actuate sameand thereby provide pressure fluid at sub stantially supply pressure tosaid percussion motor for drilling a hole, and said drilling controlvalve includes a pilot actuator in communication with said timing meansand operable to receive pressure fluid therefrom after a predeterminedtime period commencing with the actuation of said first supply valve.

5. The invention set forth in claim 4 wherein:

said timing means includes conduit means operable to be in fluid flowcommunication with said source of pressure fluid and said pilot actuatorof said drilling control valve, adjustable valve means interposed insaid conduit means, and reservoir means interposed in said conduit meansbetween said adjustable timing valve and said drilling control valvepilot actuator, and said timing valve means is operable to control therate of flow of pressure fluid from said source into said reservoir.

1. Improved rock drilling apparatus comprising: an elongated support; afluid operated rock drill movably mounted on said support and having apercussion motor operable to actuate a drill steel; a fluid operatedfeed motor mounted on said support operable to feed said drillreversibly therealong; a source of pressure fLuid; a conduit incommunication with said source and said percussion motor; flow controlmeans interposed in said conduit operable to reduce the quantity ofpressure fluid flowing to said percussion motor; a first supply valve insaid conduit actuatable to supply pressure fluid to said percussionmotor for collaring a drill hole; a second supply valve in communicationwith said source and said percussion motor operable to supply pressurefluid to said percussion motor at substantially supply pressure; and,control means operable to actuate said first supply valve to supply areduced quantity of pressure fluid to said percussion motor, saidcontrol means including timing means responsive to the actuation of saidfirst supply valve for operating said second supply valve after apredetermined time period commencing with the actuation of said firstsupply valve.
 2. The invention set forth in claim 1 wherein; said timingmeans is operable to vary said predetermined time period.
 3. Improvedrock drilling apparatus comprising: an elongated support; a fluidoperated rock drill movably mounted on said support and having apercussion motor operable to actuate a drill steel; a fluid operatedfeed motor mounted on said support operable to feed said drillreversibly therealong; a source of pressure fluid; a conduit incommunication with said source and said percussion motor; flow controlmeans interposed in said conduit operable to reduce the quantity ofpressure fluid flowing to said percussion motor; a first supply valve insaid conduit including a pilot actuator operable when supplied withpressure fluid to actuate said supply valve to supply pressure fluid tosaid percussion motor for collaring a drill hole; a second supply valvehaving a pilot actuator and being in communication with said source andsaid percussion motor for supplying pressure fluid to said percussionmotor at substantially supply pressure; and, control means includingtiming means and a fluid circuit in communication with said source andsaid first and second supply valves for supplying pilot actuator fluidthereto, a control valve in said fluid circuit operable to be actuatedto start said percussion motor by supplying pressure fluid to actuatesaid first supply valve, and said timing means is operable to providepressure fluid to actuate said second supply valve after a predeterminedtime period commencing with the actuation of said first supply valve. 4.The invention set forth in claim 3 wherein: said drilling controlcircuit includes a control valve operable to provide pilot actuatorfluid to said second supply valve to actuate same and thereby providepressure fluid at substantially supply pressure to said percussion motorfor drilling a hole, and said drilling control valve includes a pilotactuator in communication with said timing means and operable to receivepressure fluid therefrom after a predetermined time period commencingwith the actuation of said first supply valve.
 5. The invention setforth in claim 4 wherein: said timing means includes conduit meansoperable to be in fluid flow communication with said source of pressurefluid and said pilot actuator of said drilling control valve, adjustablevalve means interposed in said conduit means, and reservoir meansinterposed in said conduit means between said adjustable timing valveand said drilling control valve pilot actuator, and said timing valvemeans is operable to control the rate of flow of pressure fluid fromsaid source into said reservoir.